[SalesForce] Batch Apex: Too many SOQL queries: 201

I have created a batch apex and I get this error: Batch Apex: Too many SOQL queries: 201 while I don't have any SOQL query in a for loop. I suspect it is coming from the DatedConversionRate query but I don't see the issue.

Does anyone can help on this ?

global class UpdateFxRateForOpenOpps implements 
    Database.Batchable<sObject>, Database.Stateful {

    // instance member to retain state across transactions
    global Integer recordsProcessed = 0;
    global Database.QueryLocator start(Database.BatchableContext bc) {
        return Database.getQueryLocator(
            'SELECT ID, FX_EU__c, FX_Entity__c, CurrencyIsoCode, Entity__c FROM Opportunity ' + 
            'Where RecordType.Name IN (\'Renewals\', \'New Business\') AND isClosed=false'
        );
    }
    global void execute(Database.BatchableContext bc, List<Opportunity> scope){
        // process each batch of records
        List<DatedConversionRate> fxRates = [SELECT ConversionRate, 
                                                    IsoCode
                                             FROM DatedConversionRate
                                             WHERE StartDate=:System.today()];
        List<Opportunity> opps = new List<Opportunity>();
        for (Opportunity opp : scope) {
            if (opp.CurrencyIsoCode == 'EUR') {
                opp.FX_EU__c = 1;
            } else {
                opp.FX_EU__c = getRate(opp.CurrencyIsoCode, fxRates);
            }
            opps.add(opp);   
        }
        update opps;
    }    
    global void finish(Database.BatchableContext bc){
        System.debug(recordsProcessed + ' records processed. Shazam!');
        AsyncApexJob job = [SELECT Id, Status, NumberOfErrors, 
            JobItemsProcessed,
            TotalJobItems, CreatedBy.Email
            FROM AsyncApexJob
            WHERE Id = :bc.getJobId()];
        // call some utility to send email
        //EmailUtils.sendMessage(job, recordsProcessed);
    }
    private Decimal getRate(String oppCurrency, List<DatedConversionRate> fxRates){
        Decimal rate;
        for (DatedConversionRate r: fxRates) {
            if (r.IsoCode == oppCurrency) {
                rate = r.ConversionRate;
            }
        }
        return rate;
    }

}